A manhole is usually placed in street as a top opening for providing easy access and maintenance to the underground structure such as pipe line or sewer. The manhole is sealed by a manhole cover to avoid the falling of pedestrian or object, the manhole cover is commonly made of solid steel to support the weight of vehicles which pass over everyday. However, heavy cover also requires greater strength when it has to be removed; maintenance staff is usually equipped with basic tool such as crowbar to lift the lid. The force needed to remove the cover is slightly reduced but it still requires a strong person for operating and the disengagement of the crowbar with cover may injure the worker. Some apparatus have also be invented such as cited U.S. Pat. No. 6,202,598, entitled “APPARATUS FOR REMOVAL OF VAULT LIDS AND OTHER HEAVY COVERS”, filed by Chong et al. or U.S. Pat. No. 5,788,406, entitled “DOUBLE PIVOT SEMI-AUTOMATIC MANHOLE COVER LIFTING DEVICE”, filed by Manuel Andres Hernandez. The apparatus disclosed by Chong et al. using principle of lever, wherein wheels 20a, 20b served as fulcrum, a handle member 12 functioned as a lever and a hook member for lifting the cover. The apparatus allows the working staff to remove the cover easier than using a crowbar and is cost effective. However, the hook member 16 can be bent or broken under frequent uses which means constant maintenance and parts replacement are required. From an aspect of long term, the economic value thereof is doubtful. Further, for working in several locations in a same time, the staff team must carry multiples apparatus to save time, occupied extra space for storage and generated extra weight. Moreover, either crowbar or apparatus disclosed by Chong et al. requires a hole to be provided on the cover for engaging with the tool. The hole may allow water or other liquid penetrating the underground structure and causing damage. As disclosed in U.S. Pat. No. 5,788,406, Hernandez disclosed a manhole cover which can be lifted by a spring 84 and supported by a bar assembly 86. The user may only needed to pull and rotate the cover until its position is fixed by the bar assembly 86. To pull a cover which commonly weights 150 Kg (about 330 lbs) is relatively easier than to lift it. However, it still requires plenty strength for operating the device. Besides, the device doesn't provide any watertight feature which increases the possibility of corroding the spring 84 and bar assembly 86 by moisture, causing mal function of the device and endangering the safety of the personnel who performs maintenance. Therefore, to provide a manhole cover heavy to bear the car passing by and easy to lift with water tight feature has become the objectives of the present invention.